The investigators propose to use our previously established in-vitro model of labour augmentation and OTR desensitization (using pregnant human myometrium and an isometric tension recording device) to investigate the molecular mechanisms governing OTR desensitization and resensitization after stopping administration of oxytocin. Investigation of the signaling pathways responsible for these processes, as well as for oxytocin-induced contractions in a controlled in-vitro system will aid in the understanding of the kinetics of the OTR-oxytocin system and provide insight into potential pharmacotherapeutic targets to reduce the incidence of PPH.